Loading docks often include a dock leveler to facilitate the loading or unloading of a truck's cargo. The dock leveler provides a bridge that material handling equipment and personnel can use to travel between a loading dock platform and the bed of the truck. Dock levelers usually include a deck or ramp that can pivot about its rear edge to raise or lower its front edge. Often a lip plate extends from the front edge of the deck and is adapted to engage the rear of the truck bed. The lip plate is usually movable between a stored, retracted position and an extended, vehicle-engaging position. The pivotal movement of the deck enables the dock leveler to set the lip plate on or remove it from the truck bed.
To pivot a deck, a dock leveler usually includes some type of actuator that extends, expands or otherwise moves to force the deck upward. Downward movement of the deck may be achieved by relying on the weight of the deck (biased down dock leveler) or by physically pushing the deck back down with an external force or weight (biased up dock leveler), such as the weight of a person standing on the deck.
There are a wide variety of well-known actuators available today. Some common ones include, hydraulic cylinders, pneumatic cylinders, coil springs, high-pressure air springs, linear motors, and inflatable actuators. The subject invention pertains to inflatable actuators, which comprise an inflatable chamber disposed underneath a deck. To raise the deck, a blower discharges pressurized air into the chamber, which causes the chamber to expand and lift the deck. Upon de-energizing the blower, the weight of the deck forces the air within the chamber to backflow through the blower, whereby the chamber controllably collapses to lower the deck.
Although inflatable actuators are effective at raising a deck, the blowers of such actuators can be particularly loud. Moreover, a pit in which a dock leveler is installed can become quite dirty from the traffic across the deck and by debris infiltration from the adjacent driveway. An inflatable chamber, its blower and various other dock leveler components underneath the deck can be difficult to clean due to the limited space of a typical dock leveler pit.
Consequently, a need exists for an inflatable actuator that is quieter and easier to clean and whose blower is protected from debris.